The present invention relates to the field of intelligent telephony networks, and more particularly to the use of Advanced Intelligent Network triggers to transfer control to switch-based call processing.
Advanced Intelligent Network (AIN) is a telephone network architecture that allows network elements to instantaneously affect the routing or processing of calls based on criteria other than that of simply finding a connection path through the network. Network intelligence is decentralized off of the switch and distributed among intelligent network platforms, referred to as Service Control Points (SCPs) or adjuncts, which will be collectively referred to as SCPs. Switches such as End Offices and Access Tandems that support AIN capabilities are called Service Switching Points (SSPs). The AIN SSP is described in standards document GR-1298-CORE, xe2x80x9cAINGR: Switching Systems,xe2x80x9d Issue 5, November 1999, Telcordia Technologies, which is hereby incorporated by reference.
SCPs typically include data bases in which customer-specific information is stored for use by the network to route or affect the processing of calls. An SCP receives a query message from the SSP when the SSP requires assistance in routing a call or providing a feature. The SCP responds to the SSP with routing or processing instructions for the call. In AIN, relatively inexpensive peripheral computers can provide flexible and efficient call processing, and local carriers can design and release new calling services by modifying the SCP data. SCPs can perform a wide variety of functions, ranging from providing simple instructions or data resources to managing the overall delivery of calling services.
FIG. 1 shows a block diagram of an example of an AIN network. End Offices EO 1-A and EO 1-B are connected to Access Tandems AT 2-A and AT 2-B over voice and signaling trunks 5-A and 5-B. AT 2-A and AT 2-B are connected over voice and signaling trunk 9. Switches 1-A, 1-B, 2-A and 2-B form a traditional telephone network. Signal Transfer Point STP 3-A is connected to switches 1-A and 2-A over Signaling System 7 (SS7) links 6-A and 7-A. Signal Transfer Point STP 3-B is connected to switches 1-B and 2-B over SS7 links 6-B and 7-B. STP 3-A and STP 3-B are connected over SS7 link 10. Signal Transfer Points are network elements that route messages in the AIN network. Service Control Points SCP 4-A and SCP 4-B are connected to STP 3-A and STP 3-B over SS7 signaling links 8-A and 8-B.
AIN is based on a basic call model that describes the essential processing steps done by an SSP in establishing a two-party call. FIG. 2 shows a portion of the AIN Originating Basic Call Model through sending a call setup indication to the Called Party ID. Each major call step is indicated by a box with a numbered step name inside, e.g., xe2x80x9c1. O_NULLxe2x80x9d, xe2x80x9c7. SEND_CALLxe2x80x9d, etc. Associated with the major call steps are trigger detection points, each indicated by a box with a xe2x80x9cTxe2x80x9d. Each trigger detection point is further identified by a name, e.g., xe2x80x9c(e1) Origination_Attemptxe2x80x9d. Trigger detection points identify when an SCP can receive notification of a given event and influence subsequent call processing. Each trigger detection point typically has several associated triggers that may be set. If a trigger is set at a certain trigger detection point, and the trigger is encountered during the processing of a call and no escape criteria are met, then the SSP will suspend normal call processing and send a query message to the SCP requesting call routing instructions. Upon receiving a response from the SCP, the SSP resumes call processing per the SCP instructions.
Early versions of AIN were directed to offloading a portion of the switch intelligence, but still required the switch to keep direct control of call management. An example is the 800 number service where the extensive translation database is offloaded to an SCP. The SSP requests number translation from the SCP and then completes the basic two-party call. Current AIN allows the SCP to control a call from off-hook through on-hook. The SCP may also delegate many tasks associated with call processing to intelligent peripherals, including voice prompting, digit collecting, and voice recognition.
Each AIN trigger is defined by many attributes that describe, for example, where in the call model the trigger is, under what criteria the trigger will be activated, the address of the SCP to which the SSP will send its request message, and fault handling such as timer expiration.
It is clear from the foregoing description that AIN is firmly rooted in a query/response model. In this model, mainline call processing is suspended when an SSP trigger is encountered. At this point, the SSP formulates a query, according to the trigger definition, and transmits it to the SCP. Further processing of the call remains suspended in the SSP until a response is received. Certain timers are also started in the SSP to ensure a timely return to the suspended call. The SCP then responds to the request with a message containing call processing instructions. The SSP then resumes call processing where it left off according to the call processing instructions received from the SCP.
There is one exception to the standard query/response trigger. This is the Origination_Attempt_Authorized trigger, in which an address internal to the SSP is used for the service logic address, or local SSP feature. In this trigger, no query message is sent to an external SCP. However, this trigger still follows the query/response model in that mainline call processing is suspended, processing continues at a sub-module of the SSP, and when this processing is completed, mainline call processing continues where it left off. Timers are still set, and fault processing will be invoked if mainline call processing does not resume within a certain time limit
The invention of Applicants is an addition to AIN that allows SSP triggers to jump to internal SSP addresses for service logic, or feature, processing without a return. The invention takes advantage of the existing AIN trigger mechanism and definitions, and adds the capability of a jump to an internal SSP address for continued call processing. There is no query sent to an SCP nor the associated response message, call processing is not suspended, and there is no need for fault handling associated with the trigger.
Applicants"" invention will significantly improve feature execution time, reduce network traffic for specific high-use features that are moved from the SCP platform and coded directly in the SSP, and remove network or SCP contention and failures as a source of failure for the feature operation. While any feature that resides on an SCP could take advantage of Applicants"" invention by being directly coded in the SSP, features that do not need a large database integration (such as the 800 number service described above) are particularly well suited. As a given feature is used by a significant percentage of the subscribers in a particular office, the cost factors may be such that direct SSP coding of the feature becomes an advantage. Direct SSP coding of the feature operation reduces the link occupancy otherwise used to communicate with the SCP, and SCP outages and periods of congestion will no longer prevent the subscribers from having use of the applicable features.